<template>
<div>
    <p>请输入姓名:<input type="text" v-model="username"></p>
    <p>姓名是:{{username}}</p>
    <input type="text" v-model.number="n1">+<input type="text " v-model.number="n2">={{n1+n2}}
</div>
</template>

<script>
import {
    ref
} from 'vue'
const username = ref('zhangsan')
const n1 = ref(1)
const n2 = ref(2)
</script>
